Thoracoscopic resection of a giant esophageal schwannoma: A case report and review of literature

Introduction: Benign esophageal tumors are uncommon, accounting for approximately 2% of esophageal tumors. Esophageal schwannoma is a much rarer solid tumor with few cases reported in the literature. Open surgery is the surgical approach of choice for the treatment of esophageal tumors. With the advent of thoracoscopy, more and more countries are adopting a thoracoscopic approach to treat esophageal tumors, but there is still no clear surgical standard or modality for the treatment of esophageal tumors. Patient concerns: A 50-year-old woman was admitted to our hospital. Over the past 2 months, her clinical presentation has included progressively worse swallowing disorder and weight loss. Gastroscopy showed an elevated lesion with a smooth surface visible 18 cm out from the incisors. An electron circumferential ultrasound endoscopy showed a hemispherical bulge with a smooth surface 18 to 23 cm from the incisor; the bulge originated from the intrinsic muscular layer and showed a heterogeneous mixed moderate ultrasound with a little blood flow signal and blue-green elastography in 1 of the sections measuring approximately 4 cm × 3 cm. Chest computed tomography (CT) showed a mass-like soft tissue shadow in the upper esophagus measuring approximately 39 mm × 34 mm, with a CT The lumen was compressed and narrowed, and the lumen of the upper part of the lesion was dilated, and the adjacent trachea was compressed and displaced to the right. Interventions: After completion of the examination, assisted by artificial pneumothorax and thoracoscopic resection of esophageal masses were performed. Diagnosis and Outcomes: Postoperative pathology report: Mesenchymal-derived tumor (esophagus), combined with immunohistochemical staining results and morphologic features supported schwannoma. The patient’s postoperative course was calm. The patient’s postoperative dysphagia subsided. Conclusion: We describe a case of successful treatment of a schwannoma of the upper esophagus using artificial pneumothorax-assisted VATS. The combined use of Sox10 and S100 helps to improve the sensitivity and specificity of schwannoma diagnosis. Damage to the esophageal lining was avoided by mixed thoracoscopic and endoscopic exploration. This approach can also be applied to benign esophageal tumors in the thoracic and subthoracic segments, leading to better minimally invasive results.


Introduction
The majority of esophageal tumor lesions are esophageal cancer.The benign primary esophageal tumors which account for about 2% of all esophageal tumors are uncommon.Over 80% of benign esophageal tumors present as smooth muscle tumors and less commonly as esophageal schwannoma. [1,2]Esophageal schwannoma are characteristically neurogenic tumors of mediastinal origin.It occurs rarely and is difficult to diagnose by imaging.They are usually benign and exhibit 1 or 2 histological patterns: Antoni A and B. [3] Esophageal schwannoma are usually seen in Asian patients, with a predominance of women and middle-aged (approximately 50-60 years old) patients. [4]ne of the most common symptoms is dysphagia.Histological and immunohistochemical studies are required for diagnosis, and surgical resection is the primary treatment for the disease.A literature search was performed in the PubMed database with the subject terms "(esophageal schwannoma or Esophageal nerve sheath tumor)" and "surgery" and there were 175 studies published on this topic as of December 2022.The reference lists of all full-text retrieved were screened to further identify potentially relevant studies.The detailed search strategy is shown in the study flowchart (Fig. 1).Only 1 investigator reviewed the cases reported in the literature.The following variables were extracted for each case report: author, age, gender, symptoms, surgical procedure, immunohistochemical results, benign and malignant.
Initially, 62 case reports and series were identified in the literature, 11 of which were excluded due to incomplete data according to the previously described methodology, and 51 were finally included.Detailed patient data are available in Table 1.
This study focuses on the analysis of a 50-year-old female patient who presented with progressive dysphagia and weight loss, with a preliminary preoperative diagnosis of esophageal smooth muscle tumor and a preliminary postoperative diagnosis of esophageal schwannoma.The aim of this study was to investigate the applicability of manual pneumothorax-assisted thoracoscopic resection of giant esophageal schwannoma and the pathological features of esophageal schwannoma, and to review the relevant literature.

Methods
The patient was positioned in the left lateral position on the operating table with the operator and scope hand on the left side of the patient and the assistant on the right side of the patient.Under general anesthesia, both lungs are ventilated using a singlelumen endotracheal tube.The skin of the 8th intercostal space was incised 1 cm from the axillary midline, and a poke card was placed and normal oxygen saturation was maintained after a short period of low tidal volume (250 mL/min) single-lumen tracheal intubation.A right-sided artificial pneumothorax was created by injecting 8 to 12 cm H 2 O positive pressure carbon dioxide (CO 2 ) through the poke card and a thoracoscope was placed.Incisions of 1 cm, 0.5 cm and 1 cm were made in the anterior axillary line of the 4th intercostal space, the posterior mid-axillary line of the 6th intercostal space and the posterior axillary line of the 7th intercostal space, respectively, and poke cards were placed.Normal tidal volume (400-500 mL/min) was restored.The location of the esophageal tumor was explored thoracoscopically, and the mediastinal pleura was opened by ultrasonic knife to bluntly separate the esophageal tumor without damaging the esophageal lining.All specimens were placed in a specimen bag, and the 4th rib incision was extended until the specimen was removed.The drainage tube was disposed of through the right 7/8th rib incision and the incision was sutured as well as the drainage tube was fixed.The procedure was concluded after endoscopic exploration of the esophageal lining without damage.
Prior to surgery, the patient and family were informed of the benefits and risks of this new approach.In case of intraoperative rupture of large blood vessels or endothelial injury, alternative surgical approaches (open access or triple-incision radical esophageal cancer surgery) may be performed.Written informed consent was obtained from patients and their families, and ethical approval was obtained from the Research Ethics Committee of the Second Hospital of Jilin University.

Case report
A 50-year-old woman was admitted to our hospital.Over the past 2 months, her clinical presentation has included progressively worse swallowing disorder and weight loss.Physical examination did not reveal any problems.Gastroscopy showed an elevated lesion with a smooth surface visible 18 cm out from the incisors.An electron circumferential ultrasound endoscopy showed a hemispherical bulge with a smooth surface 18 to 23 cm from the incisor; the bulge originated from the intrinsic muscular layer and showed a heterogeneous mixed moderate ultrasound with a little blood flow signal and blue-green elastography in 1 of the sections measuring approximately 4 cm × 3 cm (Fig. 2).Chest computed tomography (CT) showed a mass-like soft tissue shadow in the upper esophagus measuring approximately 39 mm × 34 mm (Fig. 3), with a CT The lumen was compressed and narrowed, and the lumen of the upper part of the lesion was dilated, and the adjacent trachea was compressed and displaced to the right.No biopsy was performed due to the anticipated tumor resection.After completion of the examination, thoracoscopic resection of the esophageal mass was performed under general anesthesia with a single-lumen tube tracheal intubation (Fig. 4).A solid mass of 7.0 cm × 4.0 cm × 4.5 cm was removed and sent for pathological examination (Fig. 5).Postoperative pathology report: Mesenchymal-derived tumor (esophagus), combined with immunohistochemical staining results and morphologic features supported schwannoma.Immunohistochemical staining results: CD117(−), NSE(−), Desmin (focal +), CD34(−), S100(+), SMA(−), Ki67 (3% positivity), H-Caldesmon(−), DOG-1(−), SDHB(+), P53(−), SOX10(+), H3K27me3 (+).Bedside chest radiograph on postoperative day 1 showed good bilateral lung expansion and sharp bilateral rib diaphragm angles (Fig. 6A).The gastric tube was removed after a repeat chest CT on postoperative day 5 (Fig. 6B).The patient's postoperative course was calm.The patient's postoperative dysphagia subsided.

Discussion
Comparable to other submucosal tumors of the esophagus, including smooth muscle tumors and gastrointestinal mesenchymal tumors (GIST), esophageal schwannoma are usually asymptomatic.The most common symptoms, if symptoms are present, are dysphagia and chest discomfort. [5]Other reported signs and symptoms include chest pain, wheezing, vomiting of blood, cough and palpable neck mass. [6]sophageal schwannoma are most often seen in the upper, middle, and mediastinal esophagus.It is difficult to diagnose this condition preoperatively, and the final diagnosis is usually determined after resection. [7]There are several morphologic variants of nerve sheath tumors, namely conventional, cellular, microcystic/reticular, plexiform, and melanotic nerve sheath tumors. [8]sophageal schwannoma usually occur more often in women than in men, in a ratio of 4 to 1, especially between the ages of 50 and 60. [5] There have also been reports of patients with malignant schwannoma, but such cases are extremely rare. [9]me of the symptoms of this disease include dysphagia, dyspnea and chest pain, and may develop and worsen as the size of the esophageal schwannoma increases. [10]t is necessary in our current situation to obtain biopsy results by esophagogastric endoscopy to establish the diagnosis.Schwannoma is a kind of submucosal tumor and  ultrasound endoscopy guided fine-needle aspiration biopsy has been reported to be useful for both diagnosis and treatment. [11]Certain investigators have suggested that the current biopsy technique using endoscopic ultrasound-guided fine-needle aspiration has a diagnostic accuracy of 52% to 86% for submucosal esophageal tumors. [12,13]Esophageal schwannoma cells were positive for S100 protein but negative for smooth muscle markers such as actin and desmin, which were positive in smooth muscle tumors, while CD34 and CD117 were characteristically positive in GIST. [14]Recent studies have shown that Sox10 is a potential molecular biological marker for the diagnosis and differentiation of some tumors of the nervous system.Sox10 is consistently expressed in gastrointestinal nerve sheath tumors and can distinguish them from mesenchymal tumors that are interstitially S100 protein positive.Sox10 is superior to S100 as a molecular marker in terms of sensitivity and specificity for the differential diagnosis of schwannoma and fibrous meningiomas. [15,16]tudies have also shown that Sox10 is more specific than S100 for tumors of neural crest origin: Sox10 (99% specificity) and S100 (91% specificity). [17]The combined use of Sox10 and S100 helps to improve the sensitivity and specificity of schwannoma diagnosis.Benign esophageal schwannoma typically require only tumor removal, not complete resection.Identifying the submucosal surgical plane is challenging due to its size; however, ensuring the integrity of the mucosa is paramount. [18]There is a clear preference in the literature for schwannoma in the upper esophagus, so a right thoracic approach is usually chosen. [1,2,6,19]urrently, VATS is becoming increasingly popular because it is less painful and has a shorter recovery time than open thoracic surgery.Takayoshi Watanabe et al reported the difficulty of resecting esophageal nerve sheath tumors larger than 5 cm using a VATS approach and the need to convert from resection to subtotal esophagectomy. [20]Minimally invasive resection of benign esophageal tumors is technically safe and has a shorter hospital stay compared to open surgery, a retrospective study suggests.Although the exact size threshold could not be determined, most tumors larger than 7 cm were removed by open thoracotomy. [21]onetheless, there are limitations to the possibility of thoracoscopic resection of esophageal schwannoma due to the size and location of the tumor.It has been a challenge to completely resect the huge tumor without compromising the mucosal integrity due to the limitation of 2-dimensional view and range of motion of conventional thoracoscopic tools.
A thoracoscopic esophagectomy in the prone position has been reported as a safe method of treating esophageal cancer in the thoracic segment. [22,23]The thoracic/subthoracic esophagus is automatically detached from the descending aorta by gravity without ligature after mobilization of the surrounding tissues. [24]The narrow gap between the upper thoracic esophagus, trachea and artery cannot be achieved through a prone position.In contrast, the artificial pneumothorax assists in increasing the tissue gap through CO 2 filling, which   facilitates intraoperative reduction of surrounding tissue damage.
Most recently, there has been improved visibility and flexibility in esophageal surgery provided by RATS using the da Vinci Surgical System.Hecheng Li et al have performed resection of a giant esophageal nerve sheath tumor located in the posterior mediastinum by the da Vinci Surgical System.The robotic approach offers advantages over conventional thoracoscopic systems, including wrist-like motion of the instruments, 3-dimensional vision, and ergonomic comfort for the surgeon.These features facilitate a combination of sharp and blunt dissection in a narrow space, subsequently offering the possibility of complete tumor removal without interrupting the peritoneum and the surrounding esophageal mucosa. [25]Nevertheless, robotic surgery is relatively costly and unaffordable for the genpublic.In this case, the esophageal tumor was close to the incisors and was considered to be a tumor of the upper esophagus.Although the location was on the left side of the thoracic cavity, a thoracoscopic right-sided approach was still used, and a cervicothoracic-abdominal triple incision was performed for radical esophageal cancer if necessary.Resection of submucosal esophageal tumors through a thoracoscopic approach can sometimes lead to accidental opening of the esophageal mucosa. [22]To reduce the possible risk of intraoperative esophageal mucosal injury, we chose to ensure the integrity of the esophageal lining through thoracoscopic surgery and simultaneous intraoperative upper gastrointestinal endoscopy.This hybrid endoscopic and thoracoscopic approach allows the surgeon to easily perform tumor debulking without accidentally opening the esophageal mucosa.

Conclusion
In conclusion, we describe a case of successful treatment of a schwannoma of the upper esophagus using artificial pneumothorax-assisted VATS.The combined use of Sox10 and S100 helps to improve the sensitivity and specificity of schwannoma diagnosis.Damage to the esophageal lining was avoided by mixed thoracoscopic and endoscopic exploration.This approach can also be applied to benign esophageal tumors in the thoracic and subthoracic segments, leading to better minimally invasive results.

Figure 2 .
Figure2.An electron circumferential ultrasound endoscopy showed a hemispherical bulge with a smooth surface 18 to 23 cm from the incisor; the bulge originated from the intrinsic muscular layer and showed a heterogeneous mixed moderate ultrasound with a little blood flow signal and blue-green elastography in 1 of the sections measuring approximately 4 cm × 3 cm.

Figure 3 .
Figure 3. Chest computed tomography (CT) showed a mass-like soft tissue shadow in the upper esophagus measuring approximately 39 mm × 34 mm.

Table 1
Surgical resection of esophageal schwannomas: a review of the literature.